1. Field of the Invention
The present invention generally relates to solid state imaging devices and, more particularly, to a small solid state imaging device having a simple structure capable of picking up an image in a dark place, i.e., a solid state imaging device for use with an electro-endoscope.
2. Description of the Prior Art
FIG. 1 of the accompanying drawings shows an example of a conventional electro-endoscope in which an endoscope scope has on its top a small solid state imaging device which derives a picture in the form of an electrical signal.
As shown in FIG. 1, there are provided an endoscope scope a and a solid state imaging device b provided at a position inwardly and within an interior of the scope a. The solid state imaging device b receives a source voltage from a signal processing system 12 provided at the outside of the endoscope a and supplies an image signal to the signal processing system 12. Light guides c, c are made of optical fibers, for example, to emit a light supplied thereto from a light source 13 provided outside the endoscope a through the inside of the endoscope a from the top surface of the endoscope a.
An objective lens d is disposed ahead of the solid state imaging device b. A blast outlet e is used to clean smudges on the objective lens d by the jetting of air supplied thereto from an air and water conveyance system 14. A water conveyance outlet f is used to jet water supplied thereto from the air and water conveyance system 14. The solid state imaging device b and the signal processing system 12 are coupled via a wiring g. In FIG. 1, reference numeral 15 designates a control system and reference letters h denote a television monitor and i a recording apparatus.
Demands from users that the electro-endoscope be made as small as possible is unlimited and the manufacturers intend to produce smaller solid state imaging devices. However, such requirements of the users cannot be satisfied even when the solid state imaging device is made compact in size. The reason for this is that, although solid state imaging devices are miniaturized by the development of micro-lithography, the conventional electro-endoscope needs a light source provided separately from the solid state imaging device and therefore there is a large limit on miniaturizing the electro-endoscope.